The Taoiseach has insisted that parliamentary amendments to the UK Government's Brexit plans aren't a reason for Dublin to panic.

Leo Varadkar last night said "instability and turmoil" in London wasn't cause for his government to change its position regarding the border.

He was speaking after Irish Justice Minister Charlie Flanagan said House of Commons amendments to the UK Customs Bill cast "serious doubt" over Theresa May's Brexit blueprint.

Monday night's vote means there will definitely be no border down the Irish Sea. Dublin is insisting there can be no Brexit deal without a backstop to prevent a hard border. The Taoiseach said a deal was still possible, but his government will "step up our preparations for a no-deal scenario".

Mr Varadkar said developments at Westminster "shouldn't give us cause for panic, and certainly shouldn't give us any reason to change our position".

Although a no deal scenario was unlikely, he said preparations were still essential because "we can't make assumptions that the Withdrawal Agreement will get through Westminster".

He told RTE: "It's not evident, or not obvious, that the government of Britain has the majority for any form of Brexit, quite frankly."

A spokesman for Foreign Affairs Minister Simon Coveney added: "It is fully accepted and understood there can be no withdrawal agreement without a legally operable backstop ensuring that there will be no hard border."

"What we saw (on Monday) was more debacle and chaos in the Tory party. In-fighting continues as we approach a critical time in Brexit negotiations," she said. "Theresa May is trying to placate the hardline Brexiteers and the DUP, who are propping her up."

But DUP MP Sammy Wilson said his party was proud to have delivered its support in crucial parliamentary votes to "ensure the UK will have a stronger hand in negotiations with the EU". He said: "We are particularly pleased that there was no opposition to the proposal that Northern Ireland will not by law be treated any differently from the rest of the UK when we leave the EU.

"Michel Barnier can bluster, Varadkar and Coveney can foot stamp all they like, but the fact remains that the Prime Minister has now got the support of whole of Parliament in opposing their demands that Northern Ireland would stay in the single market and customs union."

Ulster Unionist MEP Jim Nicholson said Northern Ireland's position as an integral part of the UK was not expendable in Brexit negotiations, no matter how much nationalists may wish otherwise. He welcomed the news that plans for "an internal UK border" had been "well and truly kicked into touch".